Saturday, March 18, 2017

New research has suggested that humans could have been a crucial factor in the creation of the Sahara desert. A new report by archaeologists and ecologists from Seoul National University in South Korea, and published in the journal Frontiers in Earth Science, has investigated the role of human activity within the desertification of the Sahara. This is because, for a brief period around 10,000 years ago, the area was a rich and luscious green land covered in lakes. According to the report, the period began when "African neolithic communities experimented with pastoral agriculture near the Nile river around 8,000 years ago". This technique then gradually began to move westwards. As the communities began to expand and spread, an increasing number of livestock was introduced, and more vegetation was removed in order to house them.

By chopping down so much vegetation, the ground was reduced to scrub which had no cover from the sun's powerful rays, and therefore increased the amount of sunlight that was reflected back from the Earth's surface, rather than being absorbed, which is called its albedo. In turn, this can influence the atmospheric conditions of the surroundings. Following this occurrence, a reduction in monsoon rainfall was then sparked, which led to further desertification and vegetation loss. This soon led to a vicious circle which continued to spread further and further, before eventually transforming an area almost as big as the United States into a hot desert.

These new findings have challenged previous research which believed that the changes to the Sahara area were caused either by changes in the Earth's orbit or natural changes in vegetation. The activity of Neolithic humans has also been known to drive ecological change in parts of Europe, East Asia, and the Americas. An example of this is that some speculate that Madagascar was shaped by humans through extensive man-made forest fires around 1,000 years ago. Therefore, a similar occurrence could have happened to create the Sahara as it is today. However, further research needs to go into this theory, which researchers hope to conduct by returning to the desert and examining what lies beneath the sand. Project leader Dr David Wright said in a statement, "There were lakes everywhere in the Sahara at this time, and they will have the records of the changing vegetation. We need to drill down into these former lake beds to get the vegetation records, look at the archaeology, and see what people were doing there. It is very difficult to model the effect of vegetation on climate systems. It is our job as archaeologists and ecologists to go out and get the data, to help to make more sophisticated models."

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